![]() synthesized PPy-coated Fe 3O 4 by in situ polymerization, and not only applied these particles to ER fluid, but also to magnetorheological (MR) fluids. Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) coated polystyrene (PS) particles via a simple physical adsorption procedure, monodisperse polypyrrole (PPy)-coated silica particles using 3-(trimethoxysilyl)propyl methacrylate as a modifying agent to enhance the chemical affinity between core and shell, and core-shell structured PS/poly(diphenylamine) via a controlled-releasing process with chemical oxidative polymerization were reported. encapsulated PANI by poly(methyl methacrylate) (PMMA) via a simple physical adsorption route in aqueous media, in which the high conductivity of PANI was controlled by the insulating PMMA shell. ![]() Many ideal core-shell-type microspheres have been applied to ER fluids. In addition, a core-shell structured ER material composed of a conductive material and an insulating material can effectively prevent the electrical breakdown that occurs easily during the ER test process. One of them is the synthesis of core-shell typed microspheres by encapsulating irregular materials with a microspherical shape or coating electro-responsive materials on monodispersed spherical core. Therefore, to understand the ER mechanism better, many studies have been interested in synthesizing spherical ER materials using various methods. įurthermore, the spherical morphology of ER materials is a critical factor in their theoretical models, but many actual ER materials have an irregular morphology. Several methods have been used to improve these problems, such as synthesis of composites, and synthesis of PANI with a regular morphology using a template. On the other hand, pristine PANI also has some defects as an ER material, such as high current density, easily leading to electric breakdown in high electric field strengths irregular morphology and colloidal instability. Furthermore, the properties of ER fluids based on different forms of PANI synthesized by different methods have been studied extensively. Polyaniline (PANI), which is one of the most promising and extensively investigated conducting polymers, has been applied extensively to several areas, such as supercapacitors, catalysts, sensors, and biological fields, because of its electro-activity, environmental and chemical stability, controllable conductivity, biological compatibility, ease of preparation, and low cost. Recently, conducting polymer materials have been studied widely in many fields because of their low density, good thermal and chemical stability, reproducibility, and controllable conductivity. Owing to these characteristics, ER fluids have potential applications as dampers, clutches, brakes, robotics, and finishing. ![]() Moreover, the shear viscosity always exhibits obvious shear thinning behavior. On the other hand, in the presence of an electric field, the ER fluids exhibit Bingham fluid-like behavior, in which the shear stress remains stable in the low shear rate region and increases with increasing shear rate in the high shear rate region. ER fluids usually exhibit Newtonian fluid-like behavior in the absence of an electric field, in which the shear stress increases linearly with increasing shear rate and the shear viscosity shows an almost constant value. Therefore, the behavior of ER fluids in an electric field, such as shear stress, shear viscosity, and dynamic modulus, can be quite different from those in the absence of an electric field. Under the application of an external electric field, the initially freely and randomly dispersed particles in the ER fluids aggregate and form chain-like structures, which undergo deformation and destruction in a shear flow perpendicular to the electric field and recombine continuously in an applied external electric field. ![]() Electrorheological (ER) fluids are a type of intelligent and smart material, generally consisting of electrically polarizable or semi-conducting materials dispersed in an insulating medium, which are in a fluid-like state in the absence of an electric field and exhibit an almost instantaneous transition to a solid-like state under an applied external electric field. ![]()
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